1. Field of the Invention
This invention relates to storage systems that include a plurality of storage devices. More particularly, the invention relates to a method for assigning a reliability rating for a group of storage devices based on information indicating one or more operational characteristics of the storage devices in the group.
2. Description of the Related Art
Computer systems use storage devices such as disk drives to store data. The amount of data businesses and individuals store keeps increasing. This results in use of larger capacity storage devices and an ever growing number of these storage devices. Some large-scale storage systems use hundreds or thousands of disk drives to store large amounts of data. Disk drives are prone to failures that can cause the stored data to be permanently lost or else require considerable time and effort to recover the data. In a large-scale storage system with many disk drives, there is a high likelihood of multiple disk drive failures. The larger capacity of the storage devices makes data loss and/or, recovery as a result of a failure more expensive. Also, the larger number of devices increases probability that more of those devices will fail. Therefore, it is desirable to predict disk drive failures before they occur so that preventative measures against data loss can be taken.
Most existing methods for predicting disk drive failure focus on predicting failure of an individual disk drive by analyzing that disk drive's behavior. In other words, these methods analyze various aspects of a particular disk drive's behavior and attempt to find signs indicating that that particular disk drive is likely to fail. However, studies have shown that a majority of disk drive failures occur without any warning or predictive signs.